The Langmuir-Blodgett's technique is known as a method of forming a monomolecular film on a substrate.
In this technique, the monomolecular film is formed on the substrate by spreading a monomolecular film on a gas-liquid interface and transferring the monomolecular film onto a substrate. A compound having a surface activity, for example, a compound having hydrophilic and hydrophobic groups in its molecule is used as a compound for forming the monomolecular film.
On the other hand, the following methods are generally known for forming on a substrate a particle layer from solid particles having no surface activity.
(1) The one method comprises spreading on a substrate a dispersion comprising a dispersing medium and, dispersed therein, solid particles, for example, a spherical-polystyrene suspension (latex) and thereafter evaporating the dispersing medium to thereby form a two-dimensional crystal layer, for example, a monoparticulate layer (Hyomen (surface), Vol. 31, No. 5, pp. 11-18 (1993)).
(2) The other method comprises contacting a dispersion comprising a dispersing medium and, dispersed therein, solid particles with a liquid immiscible with the dispersing medium to thereby cause the liquid-liquid interface to adsorb the solid particles of the dispersion so that a monoparticulate layer is formed at the interface and thereafter transferring the monoparticulate layer onto a substrate to thereby form the monoparticulate layer on the substrate (Japanese Patent Laid-open Publication No. 2(1990)-307571).
However, the formation of the particle layer on the substrate according to the above methods encounters problems such that the resultant particle layer is inferior in adhesion to the substrate.
With respect to semiconductor devices or electronic devices having multilevel interconnection structures, an irregular surface (step) on the substrate is formed during the respective manufacturing processes, so that occasionally the planarizing of the step is required.
For example, each layer of a semiconductor device having multilevel interconnection structure has a step between wiring and nonwiring parts thereof, so that the step must be eliminated to thereby attain planarizing prior to formation of an upper wiring layer. Further, with respect to a color-filter-formed transparent electrode plate of a liquid crystal color display device, the step of the color filter must be eliminated, to thereby attain planarizing during the process of manufacturing the same. Still further, with respect to a TFT-formed transparent electrode plate for use in liquid crystal displays and the like, it is needed to eliminate the step of the TFT formed thereon to thereby attain planarizing during the process of manufacturing the same.
The present invention has been made in the above circumstances. Thus, objects of the present invention are to provide a method of forming on a substrate a particle layer highly adherent to the substrate, a method of planarizing an irregular surface of a substrate and a particle-layer-formed substrate having a highly adherent particle layer formed on a substrate.